Refrigeration



SePt 9, l941- c. c. cooNs Erm.` 2,255,415

REFRIGERATION Filed Julyzo; 1938 Y INVENTOR Curtis L. 60ans Wlliam H. If'ttto Patented Sept. 9, 1941 t.

2,255,415 BEFBIGEBATIQN Curtis C.

Kitto, Canton, Ohio, Company, North Canton, Ohio,

Coons, North Canton, and William Il.

asslgnors to The Hoover a corporation of vApplicationV my zo, ms, serial No. 22am 17 Claims.

This invention relates to refrigerating systems and more particularly to evaporator structures for such systems. 1 v,

In refrigerating systems as heretofore constructed, the refrigerating fluid owed downwardly through the evaporator byv gravity. We

Great Britain August 202,A 1931 systems which are controlled by a cycling control have the disadvantage that there is a time lag have discovered an entirely new principle of' evaporation wherein the refrigerant -iluid is caused to circulate upwardly through the evaporator against the force of gravity by the energy supplied from a propelled stream of inert gas iiowing through the evaporator. The broad aspects of this principle are disclosed and claimed in our cofpending application, Serial No. 220,189 led July 20, 1938.

between energization of the boiler heaterand the circulating lfan and the production of refrigeration; this is due to the time required to bring the boiler up to a boiling temperature. Our present evaporator automatically overcomes this diiculty by storing refrigerant liquid between active cycles whereby to produce Arefrigeration im- While it is possible te drag or sweep the liquid refrigerant through the evaporator from the low- I est to the highest points thereof, it is not always desirable to do so. It maybe desirable to use n evaporator conduits of such diameterrthat the inert gas stream will not ow therethrough with a velocity high enough to drag or sweep the liquid f refrigerant along therewith; the height of the evaporator may be so great that the gas circulating through the evaporator-absorber system is not placed under sumcient pressure to lift the liquid refrigerant entirely through the evaporator; the inert gas may be too light to elevate the liquid through the, full height of -the evapo rator; and withsome systems it may be desirable to extend the evaporatorl below the condenser non. V y

Wev have further discovered that a'refrigerating system embodying anevaporator in which the and to connect, the two by a short direct connecliquid is dragged or swept through the system by a propelled stream ofl inert gas is self-regulating for atmospheric temperature changes. That is, the system automatically regulates itself to compensate for changes tions in atmospheric temperature conditions, thus dispensing with complex andv cumbersome -auxiliary equipment for compensating the system for changes in atmospheric temperature changes. An evaporator in which the liquid refrigerant is dragged or swept therethrough by a propelled induced therein by varian `mediately lthe circulating fan is energized.

' The principles above discussed are capable of expression in various structures. This application is concerned primarily with structures in which the liquid refrigerant is supplied to an intermediate evaporator level from which point 'the liquid is elevated through the evaporator to the top thereof and is then drained to the bottom of the evaporator.

Other objects and advantagesof the invention will become apparent as the description proceeds when taken in connection with the accompanying drawing in whichzfA y, l]

The singleilgure represents a diagrammatic il-v lustration of a three uid refrigeratlng system having the evaporatorl thereof shown in perspective and on anV enlarged scale.

We haveillustrated our invention as applied to a continuous three fluid absorption refrigerating system comprising a boiler B, an analyzer D,- a rectifier R, an air-cooled condenser 0,' an evaporator E, an air-cooled absorber A, and a pressurev equalizng medium circulating fan F driven by an electrical motor G. With the ex- V that the system is suitably chargedwith a restream of inert gas is well adapted to multi-temperature operation. l More specifically, an evaporator in which the inert gas drags or sweeps the liquid upwardly Vtherethrough automatically adapts itself to a structure having a low tempera- 3 ture freezing section and a higher temperature box-cooling section.

Previous three fluid absorption refrigerating frigerant, such as ammonia, an absorbent, such as water, and a pressure equalizingmedium, preierably a dense inert gas such as nitrogen. -The boiler B is heated in any suitable manner as by a gas burner or an electric cartridge heater, it being understood that the source of heat to the boiler and the electrical motor G are controlled in-any suitable or approved manner. A suitable control mechanism is disclosed-in the co-pending application of Curtis C. Coons, filed June 1'1, 1937, Serial No. 148,424.

f Refrigerant vapor generated by the. application of heat to the solution of refrigerant and abair-cooled absorber A. The inert ing downwardly therethrou erant vaporis separated from the inert gas by absorbent contained in the boiler B passes upwardly through the analyzer D in counterow to strong liquor supplied thereto from a source to be described hereinafter whereby the refrigerant vapor is substantially freed of vapor of absorption liquid. Refrigerant vapor is conveyed from the analyzer D to the condenser C by way of a conduit II. An air-cooled rectifier R, which is included in the conduit II, causes-condensation of any vapor of absorption solution which may pass through the analyzer D. 'I'he refrigerant vapor is liquefied in the condenser C, which ex-1 tends well below the top portion of the evaporator, preferably by heat exchange with the surrounding air, and is discharged therefrom through a conduit I2 leading to the evaporator.

The exact operation of the evaporator will be explained in detail hereinafter. For the present it is sumcient to note that the liquid refrigerant is discharged into the evaporator through the conduit I2 and evaporate's into a propelled stream of inert gas to produce refrigeration. The mixture of inert gas and refrigerant vapor produced in the evaporator is discharged from the boxcooling section I3 thereof into theinner conduit Il of a gas heat exchanger I5. The conduit Il communicates with the lower end of a tubular gas refrigerant vapor -mixture passes upwardly through the absorber A in counterow to absorption liquid ow.-

gh whereby the refrigsorption. The inert gas is discharged from the absorber A into the suction inlet of the circulating fan F through a conduit I6. The fan places the inert gas under pressure and discharges it through a conduit I'I into the outer path of the gas heat exchanger I5 from which it is returned to the evaporator through a conduit I8.

The weak liquor formed in the boiler by the generation of refrigerant vapor is conveyed therefrom to the upper end of the absorber A through a conduit which in part forms the inner member of a'liquid heat exchanger 2|. The weak absorption solution iiows downwardly. through the absorber A in counteriiow tol the inert gas refrigerant vapor mixture passing upwardly therethrough whereby to produce strong absorption solution. 'I'he strong solution flows to the low-point of the conduit I4 from which it is drained by a conduit 22 into a strong solution reservoir 23. VThe strong solution is conveyed from the reservoir 23 to the liquid heat exchanger 2l by a conduit 24. A conduit 25 conveys strong solution from the liquid heat exchanger 2| into the analyzer D.

The absorber A is at an elevation' higher than the boiler-analyzer system B-D wherefor the weak liquor en; route-to the upperv end of the absorber A must be elevated thereinto. yA con- 'duit 2'I is connected to the `gas discharge conduit II of the fan Fand to the conduit 20 below the liquid level in the boiler-analyzer system whereby the lweak solution is elevated/ through the conduit 20 into the upper end vof the absorber by gas-lift action.

Referring now to the evaporator E in detail, it n will be seen that it comprises a coil section 29 constituting a low temperature or ice-freezing' section and a high temperature -box-cooling section I3 provided with a plurality of air-cooling fins 3l. It will be seen also that the box-cooling conduit I3 is considerably larger in diameter than the coil section 29. y

' As illustrated, the coil section 29 of our evaporator comprises a plurality of parallel coil sections positioned in vertically spaced horizontal substantially equal distances apart. The. U`

shaped portions of each coil section are serially connected together by a conduit extending across the rear of the evaporator and connecting the outer leg elements thereof. The inner legs of the U-shaped portions of each coil section form the inlet and outlet connections thereof. One inner leg element of the lowest coil section forms the inlet thereof, and the other inner leg element of the lowest coil s ectiomis connected to the superposed inner leg element of the superposed coil section. This process is continued for as many coil sections asl may be desired, until the section subjacent the top coil section is reached. The top coil section is provided with but one inner lleg element; the other leg element thereof is replaced by'an elevated enlarged conduit forming a box-cooling coil. The inner leg element of ,thel top coil section is connected to the subjacent inner leg element of the subjacent coil section'. .Thus it will be seen that our evaporator may be formed of a single tube bent into the desired shape whereby to form a plurality of serially connected coil elements forming shelves in vertically spaced'horizontal planes.

The evaporator will now'be described in detail with respect to the accompanying ldrawing and the reference characters marked thereon. For

purposes of convenience, the description will proceed with respect to the direction of inert gas flow through the evaporator. It vhaspreviously been notedthat inert gas is led into the evaporator through the conduit I3. The conduit I3 opens into one inner leg 32 -of the bottom coil section 30. The inert gas passes through the coil section 30 and is discharged therefrom through the other inner leg 33( into the riser conduit 34 which communicateswith an inner leg 35 of the central coil section 36. The inert gaspasses through the -cenral coil section 36 and is discharged therefrom hrough the inner leg element 38 into the riser conduit 39 which opens into the inner leg element 40 of the top coil 4I. The inert gas is discharged into the box-cooling conduit I3 through the riser conduit 42 after passing through the top coil section 4I. The inert gas then passes rearwardly through the large diameter box-cooling conduit I3I to the gas heat exchanger l5.

Liquid refrigerant is supplied through the condenser discharge conduit I2 into the central portion of the rear cross connecting conduit 31 of the central coil section 36.

The coil sections 3U' and 36 form convenient shell supports whereby the evaporator may be readily enclosed'in a casing with trays or tray from which position it curves upwardlyrto join the element 35. vThe leg portions of a small diameter U-shaped conduit 52 are connected to the conduits I8 and 50 a slight distance above the plane of the lowest coil section 30.

A drain conduit 55 extends between the strong liquor line 24 and the legelement 33 adjacent l una la.

the riser conduit 34; This drain relieves the bottom coil section 30 of excess liquid refrigerant and allows foreign bodies to escape from the evaporator coils.v Foreign bodies, such as absorption solution, which' reach the evaporator from the condenser are circulated through the evaporator with the liquid refrigerant and into the drain 55.

In order to describe the operation of the machine, it will be that it has not been' operating and that the evaporator is warm. The control mechanism will energize the motor G and the heater for the boiler B. Liquid refrigerant will discharge into the conduit 3l from the pipe I2 shortly after heat is applied to the boiler B`.

' The inert gas supplied to the conduit I willapass through the evaporator, but it will also by-pass through the conduits t and 52, as a result of which the velocity of the gas passing through the coil sections 3d, 36 and 4I is low. The liquid refrigerant will spread through the coil section 36 in both directions from-the conduit IZ. After a short period of time liquid refrigerant will begin to ow downwardly into the U-shaped portionl of the conduit 5e anawiu eventually 'mock that conduit. The liquid will continue to accumulate in the conduit 59 until it overflows through the U-shaped conduit 52 into the inert gas inlet con- At this time the conduits. 50 and 52 will'be blocked and the inert gas will cease to by-pass therethrough. The velocity of the inert 'gasowing through the coil sections will reach a high value as soon as the conduits 56 and 52` are blocked. Inert .gas passing through the central coil section 36 will now sweep the liquid refrigerant supplied thereto along with it to the riser conduit 33. A finely divided body of liquid refrigerant will be supported in the riser conduit 39 by the inert gas stream which will blast or sweep its way therethrough in a continuous stream.

The frictional drag and impact of the gas will tion 4 l The inert gas will then propel the liquid re frigerant through the upper coil section 4I and through the elevating conduit 42 into the boxcooling conduit I3. The boxcooling conduit I3 is preferably inclined slightly downwardly from front to rear whereby the liquid refrigerant blown thereinto' may flow along the bottom thereof by s factorsresults in willproduce the desired conditions. The lifting `power' of the inert gas stream is a function of its density. pressure, and velocity of `iow through the evaporator. In general, an increase in the valuev of any one or moreof the above enumerated an increase in the lifting power of the inert gas. Other things being equal, the velocity of the inert gas will be a function of the effective cross-sectional area of its path of flow;

carry part of the liquid upwardly ,into coil secs an increase in effective cross-sectional area of that path resulting in a decrease in gas velocity. For example,'it has been found that a propelled stream of mtrogen'will circulate liquid ammonial upwardly through an evaporator constructed of approximately one-half inch inside diameter tubing and having a vertical height of approximately ten inches, a pressure differential of between two and four'inches of water between the gas inlet and outlet connections to the evaporator, and with the total system pressure ranging between 270 and 400 pounds per square inch.. The above dimensions are cited by way of example only and rre not limiting in any sense.

l It has been observed in the operation of Athis type of evaporator that it frosts evenly through-l out including the pipe section 35 and the outer right hand conduit of the central evaporator coil section 36. It is not definitely known whether refrigeration isproduced in these portions of the evaporator by liquid refrigerant owing counter to the inert'ga's stream backwardly toward the connection of the drain conduit 50, or by liquid carried up into that conduit from the leg section 33 of the lowest coil section through the riser conduit 34. or merely by the very cold inert gas stream passing therethrough..

If desired, a small dam 60 may be placed in the legportion 35 of the' central coil section 36 adjacent the point of connection between thedrain conduit and the leg element 35. This dam functions to collect a quantity of liquid refrigerant when. the machine is first started and it also functions to collect liquid in the evaporator and liquid discharged'through the conduit I2 after the motor G has been de-energized.

Without the darn this liquid would merely be wasted through the drain system. VWhen the control mechanism re-energizes the boiler heater and the,I circulating fan, a quantity of liquid will be present in the evaporator to produce refrigeration during the interval between re-energization of the system and the ltime at which thev fullA boiler-condenser system into operation. y

It will be seen from the description and draw-y ing vthat liquid refrigerant is supplied first to COmBS the'central coil section 36 and that lean inert cabinets, it has been found advantageous tocirculate the inert gas through the evaporator under conditions such that the volume of the inert gas will be several hundred times gas is supplied to the bottom coil section 30. The coil sections 30 and 36 carry the main freezing load because the ice trays will rest thereon; hence it is desirable that they operate at' ylow temperatures. The evaporatorA is designed in such fashion-that vthe coil sections 30 and 36 will operate at very low temperatures. It is apparent that the inert gas stream passing through the riser conduit 39 will be relatively rich due Y Ato evaporation which has occurred in the coil the inert gas through theevaporator will be ma- .y

terially greater than the velocity of flow of the liquid refrigerant. f This evaporator meets that condition ideally while circulating the liquid refrigerant upwardly through all portions vof the evaporator. Several factors have a materialY bearing on the design of an apparatus which sections 30 and 36. Because of the relatively high vapor pressure of the-refrigerant in the inert vgas stream passing into conduit 40. evaporation will occur in the coil section 4I at a tem- 'perature higher Vthan those'prevailing in the coil sections 30' and 36, which will further increase the vapor pressure of 'the ammonia in the inert Igas stream whereby 'any evaporation occurring in the box-cooling conduit I3 will be at aV still higher temperature. Preferably the box-cooling conduit I3 and the fins 3| thereon are designed in such fashion that the surfaces' coil section 36 is sufficiently rich in refrigerant vapor to prevent excessive evaporation of the` large quantity of liquid supplied to that coil section.

From the description it will be Seen that our evaporator and gas inlet conduitA may conveniently be ymade of a single tube bent to the proper shape and'welded to the gas heat exchanger and the box-cooling conduit I3. Preferably the box-cooling conduit |73 is reduced in diameter immediately beyond its point of connection with the drain conduit 50 whereby to facilitate drainage through the conduit 50. We have provided a refrigerating system in which a positively propelled stream of inert gas travels through the evaporator at .a pressure slightly above that generally prevailing within the system and at a suiliciently high velocity to sweep or carry liquid refrigerant along with the inert gas stream and to elevate it a substantial distance through portions of the evaporator.

The liquid in the evaporator has a throttling effect on' the inert gas passing therethrough. This is very useful as it provides a fully automatic regulating system for the flow of inert gas through the evaporator.

need not be as high at low room temperatures the particular embodiment of the invention disclosed herein, the velocity'f gas flow through the evaporator is of the order of a few feet per second if a dense gas, such as nitrogen, is utilized.

The flow of inert gas through the evaporator lis substantially continuous andv steady though there is a pressure gradient from the inlet to the outlet portions thereof due to the throttling ac- -tion of the liquid, particularly in rising conduits,

on the gas stream. This insures substantially continuous uniform propulsion of liquid through the evaporator and continuous production of refrigeratin whenever the refrigerating mechanism is operating.

While we have illustrated and described a particular embodiment of our invention, itis not limited thereto but is capable of embodiment in other constructional forms and variations with- -conduit extending to a level below said lowestl `coil section and connected between the gas outlet ofl said uppermost coil section and said intermediate coil section, and means connecting said drain to the gas inlet of said lowermost coil portion.

2. An evaporator for refrigerating systems comprising a plurality oi' serially connected coil sections positioned in vertically spaced horizontal planes. a finned box-cooling section positioned above said coil sections and serially connected thereto, means for supplying an inert gas to the lowest of said coil section and for removing inert gas fromv said box-cooling section the highest one ofl said coil sections comprising a U-shaped .conduit element connected to the inlet of said box-cooling section bymeans of a substantially L-shaped conduit, the'V lower ones of said coil sections each comprising a pair of U-shaped portions having the outer legs of the U serially con'- nected together and the inner legs of the U forming the inlet and outlet connections thereof, a drain conduit extending below said lowermost coil section and connected between the gas outlet frigerant may be briefly described as follows: In

substantially horizontal conduits the gas stream flows over a stream of liquid in the bottom portion of the conduit to which it imparts a propelling force by the frictional drag of the gas stream as it passes over the liquid. Additionally, the dragging action of the gas on the liquid serves to agitate the liquid stream which improves the gas and liquid contact therebetween and aids the evaporation process. In the elevating or rising conduits, the gas stream supports a body of liquid in-a divided state through which the gas continuously forces itself agitating such'body of liquid and blowing or dragging a portion thereof into the next evaporator conduit. Though the gas is described herein as travelling at a high velocity, this term is to be understood in a relative sense because the velocity of the gas will def pend upon the conditions prevailing in the particular system as noted above; for example, in

portion of said box-cooling section and the inlet of one of said intermediate sections, and means connecting said drain through a trap to the gas inlet portion of said lowermost coil section.

3. Refrigerating apparatus comprising a boiler,

a condenser, an absorber, an upstanding evaporator, means for conveyingrefrigerant vapor from said boiler to said condenser, means for supplying liquid refrigerant from said condenser to the central portion of said evaporator, means interconnecting said evaporator and said absorber to form a `pressure equalizing medium circuit, means for propelling a pressure equalizing medium through said circuit, said circuit being arranged to supply pressure equalizing medium under pressure to the lower portion of said evaporator and to circulate the same through said evaporator with suicient velocity to propel the refrigerant through said evaporator, and means for draining liquid refrigerant elevated through said evaporator from the gas outlet thereof to the lowest section thereof lwithout allowing the prespressure equalizing medium'circuit including a.

vertically extending evaporator and said absorber, power-driven means for propelling a dense pressure equalizing medium through said pressure equalizing medium circuit, a refrigerant vapor iiquifying means connected to said boiler vand to an intermediate portion of said evaporator, and means including a liquid seal interconnecting the top and bottom portions of said evaporator, the arrangement being such that liquid refrigerant travels upwardlyvthrough said evaporator and is then conveyed to the bottom of said evaporator through said means including a -liquid seal.

5. An absorption refrigerating system including a source of refrigerant vapor, means for liquefying the vapor, an evaporator connected to receive liquid refrigerant from said liquefying means intermediate the top` and bottom thereof, means for supplying a propelled dense inert gas to the bottom portion of said evaporator, means for conveying inert gas and refrigerant vapor from the top of said evaporator, means for conveying liquid refrigerantfrom vthe top of said evaporator to the bottom thereof, and means draining excess liquid from the bottom of said evaporator to another part of said system.

6. An evaporator comprising a plurality of vvertically spacedl lsecti ns, means for .propelling a dense inert gas'thr ugh said sections from the bottom to the top thereof, means for supplying liquid refrigerant to an intermediate section of said evaporator, means for draining liquid refrigerant from the top to the bottom of said evaporator, a dam in said evaporator constructed and arranged to impede'liquid drainingto the bottom thereof fromsaid intermediate section,

and a drain connected to the lowest section of said evaporator. f

7. An absorption refrigerating apparatus including a inert gas circuit including an up standing evaporator and an absorber, a solution circuit includinga boiler and said absorber,

means for liq'ueiying refrigerant vapor generated in said boiler and for supplying the same to an intermediate portion of said evaporator,

means for propelling the inert gas upwardly through said evaporator with vsufficient force to propel liquid refrigerant therethrough, and means for conveying unevaporated liquid refrigerant from the upper to the lower portion of said evaporator.

8. An absorption refrigerating apparatus in-y cluding an inert gas circuit including an upstanding evaporator and an absorber, a solution circuit including a boiler andI said absorber, a

condenser extending below the upper portion of' said evaporator connected to receive refrigerant vapor from said boile'r and to discharge liquid refrigerant to an intermediate portion of said evaporator, means for propellingl the inert gas through said evaporator with vsufficient force to therethrough, and means for conveying unevaporated liquid refrigerant from the upper to the lower portion of said evaporator. 9. An absorption refrigeratingapparatus including an inert gas circuit including an upstanding evaporator and an absorber, a solution circuit including a boiler and said absorber,

- means for liquefying refrigerant vapor generated in said boiler and for supplying the same'to an asustan Y i 5 intermediate portion oisaidevaporator, means for propelling the inert gas upwlrdly'through Y,

said evaporator with suilicient force to propel liquid refrigerant therethrough, .and means for conveying unevaporated liquid refrigerant from the upper to the lower portionlof said evaporator,

said last mentioned means including means for preventing the passage o inert gas therethrough. 10. Absorption refrigerating apparatus comprising an evaporating element in which refrigeration is produced by the evaporation of a re frigerant liquid into a pressure equalizing medium, an absorbing element in which refrigerant Vapor is absorbed in an absorbing liquid from a pressure equalizing medium, `means connecting v said element to form a pressure equalizing medium circuit, one .of such elements including a plurality of vertically spaced serially connectedv sections, a liquid supply means connected to an intermediate one of such sections, means including a liquid trapping gas flow preventing seal for draining liquidv from one oi said sections located at an elevation above said intermediate section to one of said sections located at an elevation below said intermediate section, and means in said pressure equalizing medium circuit for propelling the pressure equalizing medium upwardly through said one element under suicient pressure and velocity to distribute the liquid therethrough.

1l. Absorption refrigerating apparatus `comt prising an inert gas circuit including a plurality of elements in which a vapor exchange occurs between a liquid and an inert gas, one of said elements yincluding a plurality of serially connected portions positioned at different elevations, means for supplying a liquid to one of said portions which is positioned at an intermediate felevation, means for draining liquidfrom one of said portions which is at an elevation-above said intermediate portion to another of said portions.

which is at an elevation below said intermediate portion, and means in said inert gas circuit for propelling inert gas upwardly through said serially connectedportions with a velocity sufcient to circulate the liquid therethrough .'by the frictional drag exerted on theliquid by the inert gas.

12. Absorption refrigerating apparatus comprising aninert gas circuit including a plurality of elements in which a vapor exchange occurs between -a liquid and an inert gas, one of said elements including a plurality of serially con- ,nectedvportions positioned at different elevations, means for supplying a liquid to one of said portions which is positioned at an intermediate elevation, liquid draining means extending downwardly below said intermediate portion to form a gas flow preventing vliquid trap connecting the highest ofl said portions and said intermediate portion, means including a gas fiow preventing liquid trap for conveying liquid from said liquid draining means to the lowest ofsaid portions without emptying said rst-mentioned 'gas flow preventing liquid trap, and means in said inert gas circuit for circulating vinert gas upwardly through said portions under sufficient pressure to 'elevate the liquid therethroughby the propelling force vof the inert gas.

13, Absorption refrigerating apparatus comprising an inert gas circuit including a plurality of elements in which a vapor exchange occurs between a liquid and an inert gas, one of said elements including a plurality of serially connected portions positioned at different elevations, means ing a ilowof for supplyinr a liquid to one of said portions ywhich is positioned at an intermediate eleva means arranged tc conduct liquid without allowgas from the highest of said portions to the lowest of said portions, and means in said inerttgas circuit for circulating inert gas upward- 1y through said serially connected portions with sumcient pressure and velocity to distribute the liquid therethrough and to pass into and out of the liquid as a vapor exchange occurs between the the liquid and the inert gas.

14. Absorption refrigerating apparatus comprising an inert gas circuit including a plurality of elements in which a vapor exchange occurs between a liquid and an inert gas, one of said elements including a plurality of serially connected portions positioned at different elevations, means for supplying a liquid to one of said portions which is positioned at an intermediate elevation,

v means arranged to conduct liquid without allowing a now of gas from the highest of said portions to the lowest of said portions, means for removing vliquid from a portion of ysaid element which'is located at an elevation below said intermediate portion, and means in said inert gas circuit for circulating inert gas upwardly through said serially connected Vportions with sufiicient.

pressure and velocity to distribute the liquid therethrough as a vapor exchange occurs between the liquid and the inert gas. t

15. Refrigerating apparatus comprising an evaporator, including a plurality of vertically spaced sections, riser conduits serially connecting adjacent vertically spaced sections. means for supplying liquid refrigerant to an intermediate section of said evaporator, means for supplying inert gas to the lowest of said evaporator sections vertically spaced and for propelling the inert gas upwardly through said evaporator sections with sumcient force to elevate liquid refrigerant therethrough, and ns for draining refrigerant carried to the inert gas outlet of the highest of skid sections to the inert gas inlet of the lowest of said sections.

16. Absorption refrigerating apparatus comprising an evaporator including a plurality of sections. means serially connecting said sections. means for supplying liquid refrigerant to an intermediate portion of said evapcause the samel to be sealed against the passage of gas by the refrigerant flowing therethrough.

17. Absorption refrigerating apparatusincluding an evaporator, means for supplying liquid refrigerant to an intermediate portion of said evaporator, means for supplying a dense inert gas to the lowest of said evaporator sections and for propelling the inert gas upwardly through said CURTIS C. COONS. WnrLIAM Hr/JKITI'O.

passage of inert gas there- 

